Conventional high voltage electrical connectors, such as bushing inserts, connect devices such as transformers to the electrical equipment of a power distribution system. Typically the electrical connector is joined to another electrical device of the power distribution system, such as an elbow cable connector, with female contacts of the electrical connector mating with male contacts of the cable connector. An exemplary operating voltage for such connectors is 25 KV. Safe use and efficient performance of such connectors depends on a combination of factors.
When the electrical connector and the cable connector are joined under a load (load make switching), an arc is struck between the contacts as they approach one another. This arc is acceptable since it is generally of moderate intensity and is quenched as soon as the contact elements are engaged. However, during load break switching, as the contacts of the electrical connector and the cable connector are separated under load, ionization of materials and/or local dielectric breakdown can occur, leading to flashover. Further, during fault closure or short circuit conditions, a substantial arc can occur between the contacts, possibly resulting in catastrophic failure of the electrical connector.
Conventional electrical connectors employ a piston, which is attached to the female contact of the electrical connector. During fault conditions the piston is forced by the pressure of ablative arc-quenching gases to rapidly move the female contact into engagement with the male contact of the cable connector, thereby minimizing the arc formed therebetween. See, e.g., U.S. Pat. No. 7,059,879 to Krause and Zhao, which is incorporated herein by reference. Current piston-contact arrangements, and existing measures such as venting that address flashover, leave room for improvement.